Re: [PATCH 17/18] nvmet-tcp: control messages for recvmsg()

Sagi Grimberg
2023-04-03T12:59:30Z

On 3/29/23 16:59, Hannes Reinecke wrote:
> kTLS requires control messages for recvmsg() to relay any out-of-band
> TLS messages (eg TLS alerts) to the caller.
>
> Signed-off-by: Hannes Reinecke <hare@suse.de>
> ---
> drivers/nvme/target/tcp.c | 71 +++++++++++++++++++++++++++++++++++++++
> 1 file changed, 71 insertions(+)
>
> diff --git a/drivers/nvme/target/tcp.c b/drivers/nvme/target/tcp.c
> index 5daf16138471..75017fd5da9f 100644
> --- a/drivers/nvme/target/tcp.c
> +++ b/drivers/nvme/target/tcp.c
> @@ -12,6 +12,7 @@
> #include <net/sock.h>
> #include <net/tcp.h>
> #ifdef CONFIG_NVME_TLS
> +#include <net/tls.h>
> #include <net/handshake.h>
> #include <linux/nvme-keyring.h>
> #endif
> @@ -92,6 +93,7 @@ struct nvmet_tcp_cmd {
> u32 pdu_len;
> u32 pdu_recv;
> int sg_idx;
> + char recv_cbuf[CMSG_LEN(sizeof(char))];
> struct msghdr recv_msg;
> struct bio_vec *iov;
> u32 flags;
> @@ -1086,7 +1088,18 @@ static int nvmet_tcp_try_recv_pdu(struct nvmet_tcp_queue *queue)
> struct nvme_tcp_hdr *hdr = &queue->pdu.cmd.hdr;
> int len;
> struct kvec iov;
> +#ifdef CONFIG_NVME_TLS

Do you need this ifdef? The recv_cbuf in the cmd is not under and ifdef.

> + char cbuf[CMSG_LEN(sizeof(char))] = {};
> + unsigned char ctype;
> + struct cmsghdr *cmsg;
> + struct msghdr msg = {
> + .msg_control = cbuf,
> + .msg_controllen = sizeof(cbuf),
> + .msg_flags = MSG_DONTWAIT
> + };
> +#else
> struct msghdr msg = { .msg_flags = MSG_DONTWAIT };
> +#endif
>
> recv:
> iov.iov_base = (void *)&queue->pdu + queue->offset;
> @@ -1095,6 +1108,19 @@ static int nvmet_tcp_try_recv_pdu(struct nvmet_tcp_queue *queue)
> iov.iov_len, msg.msg_flags);
> if (unlikely(len < 0))
> return len;
> +#ifdef CONFIG_NVME_TLS
> + cmsg = (struct cmsghdr *)cbuf;
> + if (CMSG_OK(&msg, cmsg) &&
> + cmsg->cmsg_level == SOL_TLS &&
> + cmsg->cmsg_type == TLS_GET_RECORD_TYPE) {
> + ctype = *((unsigned char *)CMSG_DATA(cmsg));
> + if (ctype != TLS_RECORD_TYPE_DATA) {
> + pr_err("queue %d unhandled TLS record %d\n",
> + queue->idx, ctype);
> + return -ENOTCONN;
> + }
> + }
> +#endif

Can we consolidate this to a helper?

Something like:
static int nvmet_tcp_check_cmsg(struct nvmet_tcp_queue *queue, struct
cmsghdr *cmsg)
{
if (!IS_ENABLED(CONFIG_NVME_TLS))
return 0;

if (CMSG_OK(&msg, cmsg) &&
cmsg->cmsg_level == SOL_TLS &&
cmsg->cmsg_type == TLS_GET_RECORD_TYPE) {
ctype = *((unsigned char *)CMSG_DATA(cmsg));
if (ctype != TLS_RECORD_TYPE_DATA) {
pr_err("queue %d unhandled TLS record %d\n",
queue->idx, ctype);
return -ENOTCONN;
}
}
return 0;
}

>
> queue->offset += len;
> queue->left -= len;
> @@ -1150,10 +1176,27 @@ static int nvmet_tcp_try_recv_data(struct nvmet_tcp_queue *queue)
> int ret;
>
> while (msg_data_left(&cmd->recv_msg)) {
> +#ifdef CONFIG_NVME_TLS
> + struct cmsghdr *cmsg;
> + unsigned char ctype;
> +#endif
> ret = sock_recvmsg(cmd->queue->sock, &cmd->recv_msg,
> cmd->recv_msg.msg_flags);
> if (ret <= 0)
> return ret;
> +#ifdef CONFIG_NVME_TLS
> + cmsg = (struct cmsghdr *)cmd->recv_cbuf;
> + if (CMSG_OK(&cmd->recv_msg, cmsg) &&
> + cmsg->cmsg_level == SOL_TLS &&
> + cmsg->cmsg_type == TLS_GET_RECORD_TYPE) {
> + ctype = *((unsigned char *)CMSG_DATA(cmsg));
> + if (ctype != TLS_RECORD_TYPE_DATA) {
> + pr_err("queue %d unhandled TLS record %d\n",
> + queue->idx, ctype);
> + return -ENOTCONN;
> + }
> + }
> +#endif
>
> cmd->pdu_recv += ret;
> cmd->rbytes_done += ret;
> @@ -1175,7 +1218,18 @@ static int nvmet_tcp_try_recv_ddgst(struct nvmet_tcp_queue *queue)
> {
> struct nvmet_tcp_cmd *cmd = queue->cmd;
> int ret;
> +#ifdef CONFIG_NVME_TLS
> + char cbuf[CMSG_LEN(sizeof(char))] = {};
> + unsigned char ctype;
> + struct cmsghdr *cmsg;
> + struct msghdr msg = {
> + .msg_control = cbuf,
> + .msg_controllen = sizeof(cbuf),
> + .msg_flags = MSG_DONTWAIT
> + };
> +#else
> struct msghdr msg = { .msg_flags = MSG_DONTWAIT };
> +#endif
> struct kvec iov = {
> .iov_base = (void *)&cmd->recv_ddgst + queue->offset,
> .iov_len = queue->left
> @@ -1185,6 +1239,19 @@ static int nvmet_tcp_try_recv_ddgst(struct nvmet_tcp_queue *queue)
> iov.iov_len, msg.msg_flags);
> if (unlikely(ret < 0))
> return ret;
> +#ifdef CONFIG_NVME_TLS
> + cmsg = (struct cmsghdr *)cbuf;
> + if (CMSG_OK(&msg, cmsg) &&
> + cmsg->cmsg_level == SOL_TLS &&
> + cmsg->cmsg_type == TLS_GET_RECORD_TYPE) {
> + ctype = *((unsigned char *)CMSG_DATA(cmsg));
> + if (ctype != TLS_RECORD_TYPE_DATA) {
> + pr_err("queue %d unhandled TLS record %d\n",
> + queue->idx, ctype);
> + return -ENOTCONN;
> + }
> + }
> +#endif
>
> queue->offset += ret;
> queue->left -= ret;
> @@ -1354,6 +1421,10 @@ static int nvmet_tcp_alloc_cmd(struct nvmet_tcp_queue *queue,
> if (!c->r2t_pdu)
> goto out_free_data;
>
> +#ifdef CONFIG_NVME_TLS
> + c->recv_msg.msg_control = c->recv_cbuf;
> + c->recv_msg.msg_controllen = sizeof(c->recv_cbuf);
> +#endif
> c->recv_msg.msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL;
>
> list_add_tail(&c->entry, &queue->free_list);